How Dogs Might Protect Kids Against Asthma: Gut Bacteria

Scientists studying why pets appear to protect kids against asthma and allergies say the answer might lie in the world of bacteria that live in the gut.

A new study published Monday found that exposing mice to dust from households where dogs were allowed outdoors significantly changed the composition of gut microbes in the mice.

When the mice were then challenged with some well-known allergy triggers, they had significantly reduced allergic responses compared with mice that had been exposed to dust from homes without dogs or that weren't exposed to any dust.

Having dogs in the house "might inoculate the GI tract" of babies and lead to a more mature immune response that is less sensitive to many allergens, said Susan Lynch, an associate professor in the division of gastroenterology at University of California, San Francisco and senior author of the study, published in the Proceedings of the National Academy of Sciences.